Some times there are an intellisense problem in the views, the namespaces in the referenced assemblies don't appear in the intellisense only in views but the do appear in .cs code files in the same project..
i've tried these ways:
<pages>
<namespaces>
<add namespace="MyNameSpace" />
</namespaces>
</pages>
in the web.config file
<compilation debug="true" targetFramework="4.0">
<assemblies>
<add assembly="SomeAssembly.Name" />
</assemblies>
</compilation>
and:
<%@ Assembly Name="SomeAssembly.Name" %> <%@ Import Namespace="SomeNamespace.Name" %>
at the beginning of the view